A Fast Lagrangian Particle Model for Use with Three-Dimensional Mesoscale Models

In recent years, the air quality modelling field has seen the development of Lagrangian particle dispersion models driven by wind and turbulence predictions from three-dimensional mesoscale models. The Lagrangian models are based on a Langevin equation for the velocity of a fluid particle, and can take a number of different forms, depending mainly on the type of turbulence being simulated. We briefly review these forms, concentrating on the theoretically correct version for simulating dispersion in a convective boundary layer (CBL).